Apparatus for handling mixtures

ABSTRACT

The instant invention provides structure for removing &#34;globs&#34; of oil from water from a feed withdrawn from subsurface deposits. The &#34;globs&#34; are homogenized into the feed with a static mixer. The oil is subsequentially removed by conventional liquid separation means.

This invention relates generally to apparatus for handling mixtureswhich include at least two liquid components although it will beappreciated that the mixture could also include gaseous and/or solidcomponents.

In one preferred aspect, the invention relates to cyclone separatorapparatus for separating liquid components from a liquid mixture. Inanother preferred aspect, the invention relates to apparatus for use inthe recovery of sub-surface oil.

Generally, the oil from a well which passes upwardly from the oildeposit through the oil flow path defining structure between the depositand the surface, referred to as a "sub-surface completion" comprises aduct or line which is formed of strings of casings each of elongatetubular form. The oil which passes through the sub-surface completionmay be formed in various admixtures, for example, water and gas, the gasin particular tending to emerge from solution as the oil passing throughthe sub-surface completion becomes subjected to lessening pressure as itrises to the surface. Even at the lower end of the completion, at thelower end of the so-called "production casing", the oil water and gasesmay be present in bubbles or "globs" of relatively discrete components.The presence of these discrete components in only gross admixture maycause certain operating difficulties. For example, where it is desiredsubsequently to effect separation of oil and water components by use ofa cyclone separator, the proper operation of the cyclone separator maybe inhibited by quickly occurring variations in the physical form of theliquid as it is admitted to the separator. Thus, if the separator weredesigned to function adequately for a given gross ratio of water to oil,operation will not be satisfactory if the flow contains "globs" of oil.Furthermore, where the so-called "air lift" method is employed tofacilitate movement of the oil to the surface the presence of thesediscrete "globs" of relatively more water free oil or of gas bubbles inthe flow may present difficulties. Finally, it may be desirable to admixdemulsifier into the material pumped from the well in order tofacilitate subsequent separation, such as when using a cyclone separatorfor that purpose.

An object of the invention in relation to one preferred aspect is toprovide a method and apparatus which, at least in part avoids one ormore of the above difficulties.

An object of another preferred aspect of the invention is to improve theefficiency of separation of components of a liquid mixture.

According to one aspect of the present invention there is providedapparatus for handling mixtures which include at least two liquidcomponents comprising a cyclone separator having an elongate separatingchamber with a larger cross-sectional dimension end and a smallercross-sectional dimension end, said separating chamber having at leastone feed inlet arranged at or towards the larger end thereof, and firstoutlet means and second outlet means, said separator being incombination with a mixer device operatively connected to the separatorand in the flow path of the mixture to be admitted to the separatingchamber through said feed inlet, said mixing device being effective tohomogenously mix the components of the mixture passing therethrough andbefore admission to the separating chamber.

Preferably, the mixer is a static mixer and may comprise a plurality offixed baffles arranged to agitate and admix the liquid components. Theremay be further provided means for delivering one or more fluidmodification agents such as emulsifying agents to said mixer.

According to another aspect of the present invention there is providedapparatus for handling oil mixtures to be recovered from undergroundreservoirs, the apparatus including a duct or line disposed in a cavitybetween the reservoir and a surface thereabove and at least one mixerwhich is operatively connected to said duct or line effective tohomogenously mix at least the liquid components in the liquid mixturewhich, in use, is delivered from the reservoir to the surface.Preferably, the mixer is a static mixer.

According to yet another aspect of the present invention there isprovided apparatus for handling mixtures containing oil and otherconstituents, the apparatus comprising a primary treatment section whichincludes one or more primary cyclone separators each having inlet feedmeans and first and second outlet means said primary cycloneseparator(s) being of the type capable of handling a mixture containinga relatively high percentage of oil and of separating the mixture intofirst and second components which are discharged from said first andsecond outlet means respectively with said first component beingrelatively highly concentrated in oil and said second component being ofrelatively low concentration, the apparatus further including asecondary treatment section which includes one or more secondary cycloneseparators the or each separator including means operatively connectedto said second outlet means of said primary cyclone separator(s) saidsecondary cyclone separators further including first and second outletmeans and being of the type capable of handling mixtures containing arelatively low percentage of oil and of separating the mixture receivedfrom said second outlet means of said primary cyclone separators intofirst and second components which discharge from said first and secondoutlet means of said secondary cyclone separators respectively, saidfirst component containing substantially the remainder of the oil andsaid second component being substantially oil free, said apparatusfurther including one or more mixers either connected to the inlet ofthe or each of the separators of said primary treatment section and/oroperatively connected to the line interconnecting the separator(s) ofthe primary treatment section and those of the secondary treatmentsection.

The invention is particularly, but not exclusively, applicable where"gas lift" is employed to facilitate transport of the liquid mixture tothe ground surface, such as by introduction of gas into the liquidmixture at a location along the length of the sub-surface completion.The invention is also applicable where the sub-surface completionincludes means for admitting a demulsifying agent into the sub-surfacecompletion.

The invention is particularly applicable where the mixture to beseparated is an oil water mixture and may be employed where the mixtureis predominantly water or where it is predominantly oil and,particularly may be employed where the cyclone separator is of a kindspecifically designed for separation of mixtures of either type.

Example embodiments of the invention are further described withreference to the accompanying drawings in which:

FIG. 1 is a diagram of a cyclone separator apparatus constructed inaccordance with the invention;

FIG. 2 is a diagram of an oil processing apparatus using separatingapparatus constructed in accordance with the invention;

FIG. 3 is a diagrammatic view of a further cyclone separator apparatusconstructed in accordance with the invention; and

FIGS. 4, 5 and 6 are diagrammatic views of three forms of the invention.

In FIG. 1, a cyclone separator 10 is shown as having a separatingchamber 25 having first, second and third cylindrical portions 12, 14and 16 coaxially arranged in that order. These cylindrical portions aregenerally similar to the corresponding first, second and thirdcylindrical portions of the separating chamber of the cyclone separatordescribed in U.S. Pat. No. 4,237,006, the disclosures of which arehereby incorporated into the present specification to form part thereof.The first cylindrical portion 12 has a feed pipe 26 associatedtherewith, this being arranged to feed tangentially into the cylindricalportion 12 an inlet aperture 30 is positioned close to the end ofportion 12 remote from portion 14. The end of portion 12 remote fromportion 14 also has a circular first or overflow outlet 32 which leadsto an overflow outlet pipe 34.

A tapered part 12a of the separating chamber is positioned between thefirst and second cylindrical portions 12, 14, towards the secondcylindrical portion 14, although such tapered section is not essential.

The second cylindrical portion 14 exhibits a taper over its length,tapering from a diameter at the end adjacent part 12a equal to thediameter of part 12a at the junction between the two portions to asomewhat lesser dimension at its opposite end. Cylindrical portion 16 isof constant diameter equal to the minimum diameter of portion 14.

In the FIG. 1, the length l₁ of portion 12, its diameter d₁, the taperangle α of the tapered part 12a, the internal diameter d_(o) of theoutlet pipe 34, the length and diameter l₂, d₂ of the second portion 14,the taper angle β of the second portion 14 and the length l₃ anddiameter d₃ of the third cylindrical portion, as well as the total areaA_(i) of the two feed inlet apertures 30 may all be selected as follows,in accordance with parameters mentioned in U.S. Pat. No. 4,237,006:

    10≦l.sub.2 /d.sub.2 25

    0.04≦4A.sub.i /πd.sub.1.sup.2 ≦0.10

    0.1≦d.sub.o /d.sub.2 ≦0.25

    d.sub.1 >d.sub.2

    d.sub.2 >d.sub.3

However, not all these parameters need necessarily be so constrained.For example the outlet diameter d_(o) need not constrained to the abovelimits as described therein. Generally, though it is in any eventpreferred that the length l₂ be at least ten times diameter d₂.

As described in the specification of International Patent ApplicationNo. PCT/AU83/00028, a portion (not shown) may be added to the separatingchamber 25. In this instance however, the portion 16 terminates in anunderflow outlet 23.

In use, liquid to be separated is admitted tangentially to the interiorof cylindrical portion 12 via feed pipes 26, the more dense component ofthe liquid then travelling lengthwise through the separator to emergefrom outlet 23, whilst the less dense component emerges from pipe 34 viaoutlet 32.

The separator above described is particularly useful for separating oiland water components in an oily water mixture, more particularly wherethere is only a relatively small portion of oil present in the mixtureas applied to the separator. In this instance, then, the lighter oilemerges from the pipe 34 and the relatively more dense water emergesfrom the underflow outlet 23.

In order, in accordance with this invention, to improve the efficiencyof separation, the cyclone separator 10 has, fitted to inlet pipe 26, astatic mixer 35. This mixer is effective in use to homogenously mix theoil and water components as they enter the separating chamber 25 and hasbeen found to result in facilitated separation of components of theadmitted mixture, more particularly to reduce the possibility ofcontamination of the water outlet from the overflow outlet 23 with oil.

FIG. 3 shows a mixer 35 associated with a further type of cycloneseparator in accordance with this invention. This separator 100 has aseparating chamber 125 of generally tapered form having a first portion112 of cylindrical form which includes at one end an axial overflowoutlet pipe 134 which extends into the portion 112 a short distance anddefines an overflow outlet 132. Portion 112 also has a tangential feedinlet 126. At the end remote from outlet pipe 134, the portion 112includes a tapered portion 112a which joins with a second portion 114 ofthe separator chamber, portion 114 being tapered and leading to anunderflow outlet 123 axially positioned at the end of the separatingchamber 25 remote from outlet 132.

This separator is designed for separation of oil and water components ofa crude oil mixture as pumped from the ground. This mixture containssubstantial quantities of water and gas is intended to separate themixture into oil and gas streams which emerge from the overflow outletpipe 134 and oily water and gas streams which emerge from the underflowoutlet 123. The separator 100 is of a kind particularly described in thespecification of my co-pending patent application PG 8334 the contentsof which are hereby incorporated into the present specification to formpart thereof. As described in the last mentioned specification theseparator 100 may be proportioned as follows:

    0.1d.sub.2 ≦d.sub.3 ≦0.5d.sub.2

    0.15d.sub.2 ≦d.sub.0 ≦0.5d.sub.2

    d.sub.2 ≦1.sub.1 ≦4d.sub.2

    30°≦α≦60°

    0.8d.sub.2 ≦1.sub.0 ≦0.8d.sub.2

    5d.sub.2 ≦(1.sub.1 +1.sub.2)≦20d.sub.2

    A=(πd.sub.2.sup.2 /32n)

    11/2°≦β≦41/2°

where d₁ is the diameter of the separator portion 112 at its greatestdiameter end, d₂ is the diameter of the separator portion 114 at itsgreater diameter end, d₃ is the diameter of the underflow outlet 123, d₀is the diameter of the overflow outlet pipe 134, l₁ is the length of theportion 112 including portion 112a, l₂ is the length of portion 114, αis the half angle or conicity angle of the tapered portion 112a and β isthe half angle or conicity angle of the tapered portion 114. "A" is thetotal cross sectional area of the feed inlet 130 defined where the pipe126 breaks into the portion 112 of the separating chamber or, if thereare "n" such inlets with "n" corresponding inlet pipes 126, the totalarea of such inlets. In this instance, too, static mixer 35 is showncoupled to the inlet pipe 126.

The instances where there are more than one inlet 26 or 126 there may bea mixer 35 associated with each such inlet or they be supplied from abranched inlet pipe into which a single mixer 35 is incorporated.

The invention is particularly applicable in oil processing apparatusemploying cyclone separators, such as described the specification of myco-pending international application PCT/AU85/00293. FIG. 2 shows suchan arrangement. Here oil in a line 220 from the well head is passed tohydrocyclone 100, effective for water dispersed in oil. A line 224therefrom at the underflow outlet end carries oily water and gas to theinlet of a second hydrocyclone 10 for oil dispersed in water. Theunderflow outlet of this separator 10 is passed on a line 228 to acyclone water degasser 230 thence through an oil content measuringdevice 332 to a clean water outlet 334. Oil and gas taken from theoverflow outlet of the separator 100 passes on a line 336 to the inletof a cyclone oil degasser 338. Oil from the underflow outlet of degasser338 is taken on a line 340 through a pump 342 to an oil outlet line 344.The overflow outlet of degasser 338 is connected to a line 348 whichcarries gas from the degasser 338 through a gas compressor 350 to passthe gas via a line 352 to the line 344 so that gas is also carried onthe line 344. The gas from the overflow outlet from the degasser 230 istaken on a line 356 and added to line 348.

The overflow outlet of the separator 10 is passed to a separator 360 ofcyclone type, the overflow outlet of which carries gas, on a line 362,for admixture with gas in line 348. Oil from the underflow outlet ofseparator 360 is carried on a line 364 and is connected to line 340 foradmixture of such oil into the oil carried by line 340. A pump 366 isprovided in a line 370. Line 370 connects to line 336 and the line 346from the overflow outlet of separator 10 to separator 360. Pump 366pumps oil and gas from line 346 to return it to line 336.

In accordance with this invention, static mixers 35 are positionedrespectively in lines 220 and the line interconnecting the underflowoutlet of separator 100 with the inlet of separator 10.

Static mixers useful in the invention include mixers of the kind inwhich fixed baffles are provided in order to agitate and admix theliquid components homogenously, preferably without introducingemulification. However, kinetic mixers employing movable such asrotatable elements may be employed.

Although the use of static mixers, in accordance with the invention, hasbeen described, by way of example, in the context of their use withparticular types of cyclone separator, they may be employed with otherforms of cyclone separator.

The static mixer may be used in conjunction with cyclone separatorswhere admission of suitable demulsifying agents is made to the liquidmixture being inletted into the separator, for purposes of improvingseparating efficiency. In this case the static mixer facilitates theadmixture of the demulsifying agent. Also, in cases where it is desiredto effect oil enrichment to a cyclone separator by recovery of anenriched oil component recovery may be facilitated by including meansfor metering quantities of oil into the mixture to be separated prior toadmission to the cyclone separator. In this case, the separatingefficiency or enrichment efficiency of the separating apparatus isimproved by passing the inlet mixture through a mixer in accordance withthis invention. Furthermore, where it is desired to generally enrich anoil containing liquid by addition of further oil, the mixing efficiencymay be improved by use of a mixer in accordance with this invention.

In FIG. 4 a sub-surface completion 10 is shown having an inner or"production" casing 12 which extends from a ground surface 14 to the oildeposit 16, as well as an outer intermediate casing 20 which may, asshown, be encased at its upper end by a still further casing 22. Asusual, oil flows from the deposit 16 into the production casing 12 toflow to the surface. In accordance with this invention, however, thereis provided a location adjacent the lower end of the casing 12 a staticmixer 24 effective to homogenously mix liquid and gas components in theliquid pumped from the deposit 16 through the completion 10.

FIG. 5 shows a modification of the arrangement in FIG. 4 where theso-called air lift principle is employed. Here, air is admitted to theannular space between the production casing 12 and the intermediatecasing 20 from whence it flows into the production casing 12 at thebottom thereof, being admitted as bubbles which, by lightening theeffective density of the liquid, serve to facilitate pumping to thesurface.

In FIG. 6 the static mixer 24 is positioned in the production casingimmediately below a location at which a suitable demulsifying agent isadmitted thereinto via a duct 40. Of course, the completion 10 may havemore than one static mixer arranged at locations along the lengththereof. Various forms of known static mixer are suitable for use withthe invention. Suitable types, employing fixed flow deflecting bafflesin a tube through which the mixture flows, are for example manufacturedby Sulzer Brothers Limited, Winterthur, Switzerland. Other examplesinclude static mixers manufactured by KENICS, (Chemineer, Inc), KOMAX®and Plenty H & M Pty. Ltd.

The described arrangement has been advanced merely by way of explanationand many modifications may be made thereto without departing from thespirit and scope of the invention which includes every novel feature andcombination of novel features herein disclosed.

I claim:
 1. Apparatus for treating a mixture which contains at least oiland water components, the apparatus comprising a cyclone separatorcomprising elements, designed, sized and arranged for separating a moredense component of the mixture from a less dense component, saidseparator comprising an elongated separating chamber with a largercross-sectional dimension end and a smaller cross-sectional dimensionend, at least one feed inlet at said larger end and first and secondoutlet means, the apparatus further including means for facilitating theremoval of globs of oil present in the mixture before the mixture entersthe cyclone separator, said means comprising a static mixer deviceoperatively connected to the separator and in the flow path of themixture to be admitted to the separating chamber through said feedinlet, said static mixer device being effective to homogeneously mix thecomponents of the mixture passing therethrough before admission to theseparation chamber so as to facilitate removal of any globs of oilpresent in the mixture.
 2. Apparatus according to claim 1 wherein saidstatic mixer comprises a plurality of fixed baffles arranged to agitateand admix the liquid components.
 3. Apparatus according to claim 1,further including means for delivering one or more fluid modifyingagents to said mixture.
 4. Apparatus for treating mixtures containingoil and water which are to be recovered from underground reservoirs, theapparatus including a duct or line disposed in a cavity between thereservoir and a surface thereabove and means for removing globs of oilpresent in the mixture, said means comprising at least one static mixerwhich is operatively connected to said duct or line and is effective tohomogenously mix at least the oil/water components in the mixture whichin use is delivered from the reservoir to the surface.
 5. Apparatusaccording to claim 4 wherein there is provided a plurality of saidstatic mixers spaced along the line so that the mixture maintains asubstantially homogenous nature during delivery.
 6. Apparatus fortreating a mixture which contains at least oil and water components, theapparatus comprising a primary treatment section which includes one ormore primary cyclone separators each cyclone separator comprisingelements designed, sized and arranged for separating a more densecomponent of the mixture from a less dense component, each saidseparator comprising an elonaged separator chamber with a largercross-sectional dimension end and a smaller cross-sectional dimensionend each having inlet feed means and first and second outlet means, saidprimary cyclone separator(s) being of the type capable of handling amixture containing a relatively high percentage of oil and of separatingthe mixture into first and second components which are discharged fromsaid first and second outlet means respectively with said firstcomponent being relatively highly concentrated in oil and said secondcomponent being of relatively low concentration, the apparatus furtherincluding a second treatment section which includes one or moresecondary cyclone separators comprising elements designed, sized andarranged for separating a more dense component of the mixture from aless dense component, said separator comprising an elongate separatingchamber with a larger cross-sectional dimension end and a smallercross-sectional dimension end, the or each separator including meansoperatively connected to said outlet means of said primary cycloneseparator(s), said secondary cyclone separator(s) further includingfirst and second outlet means and being of the type capable of handlingmixtures containing a relatively low percentage of oil and of separatingthe mixture received from said outlet means of said primary cycloneseparators into first and second components which is discharged fromsaid first and second outlet means of said cyclone separatorsrespectively, said first component containing substantially theremainder of the oil and said second component being substantially oilfree, said apparatus further including means for facilitating removal ofglobs of oil present in the mixture said means comprising one or morestatic mixers either connected to the inlet of the or each of theseparators of said primary treatment section and/or operativelyconnected to the line interconnecting the separators of the primarytreatment section and those of the secondary treatment section.